Code Definition

B2100 — Door Driver Key Cylinder Switch Failure

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B2100

B2100 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B2100 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The driver door key cylinder switch detects mechanical operation of the door lock key cylinder, generating a signal used by the Body Control Module (BCM) for keyless entry confirmation, anti theft system arm and disarm logic, and remote keyless entry override functions. Code B2100 sets when the BCM detects that the driver key cylinder switch signal is invalid, stuck in one position, or otherwise outside the expected range during normal vehicle operation. Common causes include a worn or damaged switch inside the key cylinder housing, corrosion in the door harness, broken wires from repeated doo...

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